1. Field of the Invention
The invention relates to a milling cutter, in particular for milling a groove into a turbine blade footing. The invention also relates to a method for milling a workpiece using such a milling cutter and to a method for producing such a milling cutter.
2. Background Information
Turbine blades for applications within the high temperature range, for example, without limitation, turbines for aeronautics or gas turbines for installations for power generation, are nowadays produced from so-called superalloys on account of the high thermal and mechanical stresses to which they are subjected. These superalloys are distinguished, as a rule, by very high strength, for example >1000N/mm2, and high thermal stability. Common to the various known superalloys is the use of nickel as main component (>50% by weight) and chromium as another essential constituent. Superalloys of different manufacturers are on the market, known for example by the trade names Hastelloy, Inconel, Incoloy and Rene etc. One superalloy frequently used in aircraft power plants, power station turbines and turbo-superchargers is the superalloy with the name Rene 80, which has a nickel proportion of 60%, a chromium proportion of 14%, a cobalt proportion of 9.5% and in addition percentage proportions of titanium, molybdenum, tungsten and aluminum. The turbine blades, as a rule, are coated additionally in a ceramic manner.
Turbine blades generally consist of a blade vane and a blade footing, by way of which they are fastened on a support of the turbine. The blade footing has so-called slot-in grooves which have to be inserted during the production of the turbine blades.
To date, formation of such grooves has been effected by way of abrasive engineering as up to now no (end milling cutter) tools have been available which make machining possible and have a justifiable tool life. The term tool life refers in this case, in general, to the amount of machining time until the tool is worn. The tool life of milling tools commercially available today is only within the range of seconds or a relatively small number of minutes such that, sometimes, it is not even possible to machine one single slot-in groove in a continuous manner.
Accordingly there is room for improvement in tools and methods used for machining such superalloys.